Methods and apparatus for fabricating a putter club head

ABSTRACT

A no-draft putter club head is formed using an investment casting process, wherein one or more critical surfaces of the club head—i.e., surfaces with contours that affect the visual appearance of the club head when viewed from above—are formed substantially parallel to the draw direction of the mold. The mold includes an internal cavity corresponding to a putter club head shape, wherein the cavity includes a set of surfaces substantially parallel to the draw direction of the mold. This set of surfaces may include, for example, a toe surface, a heel surface, a top rail surface, and/or a hosel surface. A wax material is suitably poured or injected into the mold cavity to form a wax replica of the putter club head shape. The wax replica is then removed from the mold cavity along a line parallel to the draw direction.

FIELD OF THE INVENTION

The present invention relates, generally, golf club heads and, moreparticularly, to a method of fabricating a no-draft putter club head.

BACKGROUND OF THE INVENTION

A golfer's ability to properly line up a ball with the club head toproduce the desired ball path is largely a function of the variousvisual cues provided to the golfer by the club head during and afteraddress. This is particularly the case with putting, where the golfer'saddress and stroke direction are highly influenced by psychological andvisual factors.

It is desirable for many of the surfaces of a putter, particularly thosesurfaces that have contours visible to the golfer from above duringaddress, to be square and aligned either perpendicular or parallel tothe top rail. Traditional casting processes, however, inhibit theformation of such surfaces.

For example, referring to FIGS. 1A and 1B, it is universal practice inthe casting art to include tapered or angled surfaces (i.e., “draft”)within the mold cavity to facilitate removal of the finished part. Thus,mold 102 is configured such that surface 106 (and, consequently,matching surface 107 of part 104) is angled slightly to allow part 104to be removed from mold 102 along a draw direction 108. Draw direction108 is generally perpendicular to a separation line 105 defined by wherethe two mold halves meet.

As shown in FIG. 1B, by incorporating a draw into surface 106, there isadhesion, friction, and/or other mechanical interaction between surface106 and surface 107 as part 104 is removed from mold 102. As depicted inFIG. 2, a draft angle 202 is suitably formed between surface 106 of themold cavity and draw direction 108. In practice, angle 202 typically hasa value between approximately 1.0 degree and 2.0 degrees.

As mentioned above, it is desirable for a putter club head to includesurfaces that, when viewed from above the club head, are perpendicularor parallel to the draw direction of the mold cavity used to manufacturethe club head. Because traditional molding techniques prevent thecasting of such a design without draft (even in relatively moderninvestment wax processes) it is customary to machine various surfaces ofthe club head after casting to give the desired visual appearance. Suchmachining is time consuming and greatly adds to the cost of the golfclub.

SUMMARY OF THE INVENTION

The present invention generally provides a method for casting a no-draftputter club head using an investment casting process, wherein one ormore critical surfaces of the club head—i.e., surfaces with contoursaffect the visual appearance of the club head when viewed from above—areformed substantially parallel to the draw direction of the mold.

A method in accordance with one embodiment of the present inventionincludes providing a mold having an internal cavity corresponding to aputter club head shape, wherein the cavity includes a set of surfacessubstantially parallel to the draw direction of the mold. This set ofsurfaces may include, for example, a toe surface, a heel surface, a toprail surface, and/or a hosel surface. A wax material is suitably pouredor injected into the mold cavity to form a wax replica of the putterclub head shape. The wax replica is then removed from the mold cavityalong a line parallel to the draw direction. A putter club headfabricated in accordance with this method is characterized byprecisely-shaped surfaces which provide subtle alignment aids to thegolfer at address.

DRAWINGS OF THE DRAWINGS

The subject invention will hereinafter be described in conjunction withthe appended drawing figures, wherein like numerals denote likeelements, and:

FIGS. 1A and 1B depict the removal of a part from a mold cavity of thetype having a draft;

FIG. 2 is a close-up of a draft angle as shown in FIG. 1;

FIGS. 3A and 3B depict the removal of a part from a mold cavity inaccordance with the present invention;

FIG. 4 is a top view of a putter club head in accordance with oneembodiment of the present invention; and

5A and 5B are isometric views of exemplary putter club heads inaccordance with the present invention.

DETAILED DESCRIPTION

The present invention generally provides a method for casting a no-draftputter club head using an investment casting process, wherein one ormore critical surfaces of the club head (e.g., the top rail, the toe,the heel, and/or the hosel) are formed substantially parallel to thedraw direction of the mold.

In general, as shown in FIGS. 3A and 3B, a mold 302 in accordance withthe present invention is configured such that one or more surfaces ofthe mold cavity, such as surface 306, are parallel to draw direction108. Draw direction 108 of resulting mold 302 is generally perpendicularto the “parting line” or “separation line” 105 of the mold, i.e., theseam where two portions of the mold meet. The mold itself may befabricated from any suitable material. In an exemplary embodiment usedto form wax replicas in connection with an investment casting process,for example, mold 302 comprises an aluminum alloy.

Notwithstanding the fact that mold 302 of the present invention includesa surface 306 that is parallel to surface 307, part 304 may be easilyremoved along draw direction 108 without experiencing significantsticking, friction, or the like. Because the present invention does notrequire the incorporation of a draft or taper into one or more criticalsurfaces of the club head, the club head body, as cast, is substantiallysquare when viewed from above, and is less likely to require machining.

In general, a method of fabricating a putter club head in accordancewith one embodiment of the present invention involves aninvestment-casting or “lost-wax” process—a processing method which isdesirable due to its cost effectiveness and precise dimensional control.Conventional investment casting techniques known to those skilled in theart will not be described in detail herein. For more informationregarding such processes, see, e.g., SOPCAK, HANDBOOK OF LOST WAX ORINVESTMENT CASTING (1986), which is hereby incorporated by reference.Furthermore, while the present invention is described in the context ofan investment casting process, it will be understood the presentinvention is not so limited.

An exemplary method for manufacturing a golf club head begins with thecreation of a die or mold 302 having a club head shape formed therein,for example, a club head such as that shown in top view in FIG. 4. Clubhead 400 includes a club head body 402 and a hosel 404, wherein hosel404 is configured to accept a shaft 406. Club head body 402 has a numberof surfaces whose contours (which may be rectilinear, curvilinear, or acombination thereof) affect the visual appearance of the club head whenviewed from above by a golfer during address. Such surfaces may bereferred to herein as “critical surfaces.” In the illustrated club head400, for example, body 402 includes a top surface (or “top rail” 414), atoe surface 410, and a heel surface 412. Each of these surfaces may beclassified as critical surfaces. In addition, hosel 404 may also includeone or more critical surfaces.

It can be seen that each of these surfaces is formed substantiallyparallel to the draw direction of the mold, which in the illustratedembodiment is generally perpendicular to line 416 defined by top rail414. FIGS. 5A and 5B show isometric views of additional putterembodiments manufacturable using the methods of the present invention.Each of these club heads 400 include critical surfaces that are parallelto the draw direction of their respective molds. Such surfaces includetoe surface 410, heel surface 412, top rail 414, and one or moresurfaces of hosel 404. The putter club head designs shown in FIGS. 4,5A, and 5B are merely presented for the purpose of example.

After a suitable mold 302 has been provided, a wax material (in liquidor paste form) is then injected into the mold (or “die”) and allowed tocool to form a solidified wax pattern or “replica.” In one embodiment,the wax is a paste wax having a melting temperature of about 100 degreesC. In an alternate embodiment, however, the wax has a meltingtemperature of about 200 degrees C.

The wax material in the mold cavity is then suitably cooled. Thiscooling may be accomplished through convection (e.g., air cooling of themold), conduction, radiation, or a combination thereof. The wax form isallowed to cool to a temperature at which it may be handled, i.e.,removed from mold 302. In one embodiment, the wax is a paste wax that isallowed to cool for approximately 60 seconds to 100 seconds (preferablyabout 80 seconds) before being removed from the mold. In accordance withanother embodiment of the present invention, the wax form is allowed tocool for approximately 10 seconds to 30 seconds (preferably about 20seconds).

The resulting solidified wax pattern is then removed from the die bypulling it out along the draw direction 108. In conventional castingoperations, the lack of draft on critical surfaces would prohibit easyremoval of the finished part. In accordance with the present invention,however, the use of wax in conjunction with a metallic mold as describedabove results in a wax form that can be removed from the mold along thedraw direction and, at the same time, include one or more criticalsurfaces (e.g., toe surface, heel surface, top rail, etc.) that areparallel to the draw direction.

After the wax replica is formed, a number of such wax patterns may beattached to a central wax stick or “sprue” to form a cluster of waxpatterns. The replica is immersed one or more times into a suitableceramic slurry, allowed to dry, then immersed in a bed of suitably finesand to form a shell mold around the solidified wax. The solidified waxreplica is melted or otherwise removed from the inner chambers of theshell mold. The shell mold is then baked in a suitable oven to hardenthe shell and remove any residual. At this point, one or more hardenedshell molds have been formed. These shell molds serve as the basis formetal casting of the actual club head.

Although the invention has been described herein in conjunction with theappended drawings, those skilled in the art will appreciate that thescope of the invention is not so limited. Modifications in theselection, design, and arrangement of the various components and stepsdiscussed herein may be made without departing from the scope of theinvention as set forth in the appended claims.

1. A method for fabricating a putter club head comprising the steps of:providing a mold having an internal cavity corresponding to a putterclub head shape, wherein said cavity includes a set of surfaces parallelto a draw direction of said mold, said set of surfaces including atleast one of a toe surface, a heel surface, a top rail surface, and ahosel surface; injecting a wax material into said mold cavity to form awax replica of said putter club head shape; removing said wax replicafrom said mold cavity along a line parallel to said draw direction. 2.The method of claim 1, further including the steps of immersing said waxreplica into a ceramic slurry and firing the resulting replica to form aceramic shell mold.
 3. The method of claim 2, further including the stepof removing said wax replica from said ceramic shell mold.
 4. The methodof claim 3, further including the step of pouring a molten metal intosaid ceramic shell mold to form a finished part corresponding to saidputter club head shape.